Deformation Control Technology And Test Study On Ship Stern-Shaft Seal

Ship stern-shaft mechanical seals instrument is an important part in the ship propelling system and is widely used in open water lubricated propeller seal system. The function of stern-shaft seal is to prevent the water flowing into the cabin from the stern shaft and the stable operation of stern shaft seal is an important safeguard of the ship propulsion even the crew’s safety. There are many reasons leading to stern-shaft seal premature failure, among which, the temperature of end face is too high and the deformation of contact surface are two main causes of stern-shaft seal premature failure, and it is also the key issue to solve the stern-shaft seal premature failure. This paper aims at these questions and then studying these questions. The main work and conclusion are as follows:1. Based on ANSYS finite element analysis software, the pressure deformation, thermal deformation and coupling deformation of stern shaft seal whose rubber and carbide materials are paired was calculated and analyzed. The study demonstrates that coupling deformation is not the simple sum of pressure deformation and thermal deformation; for stern-shaft seal whose rubber and carbide are paired, pressure deformation is the main form of the deformation.2. Considering the contact surface deformation of seal generated by initial pressure, temperature distribution of seal was calculated and analyzed. The result illustrates that tapered gap is generated between the contact end faces of two seal ring by initial pressure. The gap reduces the actual contact width and increases the contact pressure. Considering the cooling effect of the media between tapered gap on the end face, the maximum temperature is generated near the inter diameter of actual contact after deformation.3. Contact surface deformation of ship stern-shaft seal with different structure and different pressure was analyzed. Under the combined effect of the structure and pressure, the working conditions of stern shaft seal having achieved the best sealing performance were obtained. The ideas that the stern-shaft seal whose rubber and carbide are paired fits ships with small tonnage and high speed were proposed.4. Improving materials paired and optimizing overall structure of sealing ring, I also perform finite element analysis about end face deformation of the new seal. The study demonstrates that for stern-shaft seals whose carbon-graphite and carbide are paired, the heat deformation is the main deformation form. Using the way that combined pressure deformation and thermal deformation to coordinate the deformation of contact end face, I have obtained the working conditions of seal to achieve the best sealing performance. The idea that the seal whose carbon-graphite and carbide are paired fits ships with low speed was came up with.5. The tested platform for the stern-shaft mechanical seals instrument based on lathe was designed. Some parameters such as temperature and deformation were tested. The tested data are in good agreement with the theoretical calculating results. Therefore, the theoretical conclusions are confirmed based on the experimental results.